LIMs have been used in various applications to move objects, for example, in a conveyance system to convey a pallet within a warehouse system. Conceptually, a LIM is a motor which has been opened out flat with the stator units lying in a linear configuration. The rotor can be replaced with a reaction plate. When the design of the LIM is based on a standard rotary squirrel cage motor, the units of the stator, known as linear induction motor units (“LIM units”) when laid flat, each consists of a three phase winding around a laminate core. When the LIM units are energised by an alternating current (AC) supply, a travelling magnetic field is produced. When the plate or rotor is in this magnetic field, a secondary magnetic field is induced in the plate. Whereas the units of the stator when energised in a rotary motor would cause a motor to rotate, when laid flat the induced magnetic field impacts a linear force in the reaction plate.
Various types of reaction plates are known. For example, U.S. Pat. No. 3,577,928 to Vicgorri teaches a reaction plate keel suspended below a vehicle to hang between stator units.
Typically, the LIM units in a LIM remain stationary and the reaction plate moves relative to the LIM units. The moving reaction plates may be subject to wear and bending stresses as they move through the conveyance system.